A primary task of the heart is to pump oxygenated, nutrient-rich blood throughout the body. Electrical impulses generated by a portion of the heart regulate the pumping cycle. When the electrical impulses follow a regular and consistent pattern, the heart functions normally and the pumping of blood is optimized. When the electrical impulses of the heart are disrupted (i.e., cardiac arrhythmia), sudden cardiac arrest may result, which inhibits the circulation of blood. As a result, the brain and other critical organs are deprived of nutrients and oxygen. A person experiencing sudden cardiac arrest may suddenly lose consciousness and die shortly thereafter if left untreated.
A well known and effective treatment for sudden cardiac arrest or arrhythmia is defibrillation. Defibrillation involves passing a current through the person to shock the heart back into a normal rhythm. There are a wide variety of defibrillators. For example, implantable cardioverter-defibrillators (ICD) involve surgically implanting wire coils and a generator device within a person. ICDs are typically for people at high risk for a cardiac arrhythmia. When a cardiac arrhythmia is detected, a current is automatically passed through the heart of the user with little or no intervention by a third party.
Another, more common type of defibrillator is the automated external defibrillator (AED). Rather than being implanted, the AED is an external device used by a third party to resuscitate a person who has suffered from sudden cardiac arrest. FIG. 1 illustrates a conventional AED 100, which includes a base unit 102 and two pads 104. Sometimes paddles with handles are used instead of the pads 104. The pads 104 are connected to the base unit 102 using electrical cables 106.
A typical protocol for using the AED 100 is as follows. Initially, the person who has suffered from sudden cardiac arrest is placed on the floor. Clothing is removed to reveal the person's chest 108. The pads 104 are applied to appropriate locations on the chest 108, as illustrated in FIG. 1. The electrical system within the base unit 100 generates a high voltage between the two pads 104, which delivers an electrical shock to the person. Ideally, the shock restores a normal cardiac rhythm. In some cases, multiple shocks are required.
Although existing technologies work well, there are continuing efforts to improve the effectiveness, safety and usability of automatic external defibrillators.